There are several known methods for disposing of harmful organohalogen compounds contained in waste gas. One method is by direct heating of waste gas at temperatures above 800.degree. C. Another method is by adsorption on an adsorbent such as activated carbon. The former method requires a large amount of fuel and evolves toxic halogens and carbon monoxide during decomposition under certain operating conditions. The latter method suffers the disadvantage that the adsorption efficiency fluctuates depending on the concentration of substances for disposal and the adsorption is inhibited by coexistent substances.
There has been proposed a method for oxidative decomposition by the aid of a transition metal oxide as a catalyst. (Japanese Patent Laid-open Nos. 22699/1976 and 47516/1991.) This method permits oxidative decomposition at comparatively low temperatures; however, it still suffers the disadvantage that oxidation is not complete and toxic carbon monoxide remains in the treated gas.
The present invention was completed to address the above-mentioned problems. It is an object of the present invention to provide a method for efficiently disposing of organohalogen compounds together with nitrogen oxides and carbon monoxide contained in waste gas by oxidative decomposition at low temperatures without the formation of toxic chlorine gas.